The producer of Mission: Impossible – Ghost Protocol forced the star to perform some pretty hairy stunts. But since Tom Cruise is the producer (and star) of this fourth feature-film spinoff of the ’60s TV series, we can assume that he wanted to assert his limber muscularity as he approaches 50. So here he is, using gluey gloves to climb the glass façade of Dubai’s Burj Khalifa, the world’s tallest building, until he is 123 floors above certain death.

This reckless bravado, which must have tested the nerves of the movie’s insurers as much as it did Cruise’s, means to demonstrate the macho masochism — the machochism, if you will, or masochismo — of a true action star, as if he were the Douglas Fairbanks or Jackie Chan of today’s Hollywood. It could also be Cruise’s way of proving, to himself and his audience, that he can still scale any heights, in an Arab emirate or at the worldwide box office. And this, not the live-action directorial debut of Pixar’s Brad Bird or today’s sneaky five-day pre-release on 400 IMAX screens, is the real news of M:I 4 — the movie’s own subtextual cliffhanger.

A bright comer in Taps, released 30 years ago this month, Cruise seized stardom by the cojones with his daredevil smile, cool shades and underpants dance in the 1983 Risky Business, a savvy, proto-John Hughes teen comedy that was made for $6 million and earned $63.5 million in North American theaters — about $170 million in current dollars. His flyboy film Top Gun grossed the 1986 equivalent of $380 million (about the same as the Harry Potter finale made this year); and in 1988 Rain Man pulled in what would be $340 million today. Behind the Pepsodent grin, audiences saw Cruise’s steely determination to excel: that unusual amalgam stoked a quarter-century of star power.

By the time of Rain Man, the kid was 26 and not cruising but cresting. A Few Good Men, Interview With the Vampire, Jerry Maguire and the first Mission Impossible propelled him through the ’90s; two M:I sequels and a couple of Spielberg epics — Minority Report (probably Cruise’s smartest action film) and War of the Worlds — kept his streak alive into this century. Even the lamoid Vanilla Sky earned $100 million a decade ago. Note that many of Cruise’s films from his prime period were not straightforward action adventures but tough dramas, like Oliver Stone’s Vietnam bio-pic Born on the Fourth of July ($70 million then, $135 million today), to which Cruise attracted his huge and faithful fan base.

But gravity and shifting winds exert no less a pull on the loftiest stars than on a dude clinging to a Dubai skyscraper. Cruise took a hit for his public declarations of fealty to the “Church” of Scientology (a stigma that John Travolta, another Scientology proselytizer, somehow avoided). And his love sonnets to Katie Holmes, frantically declaimed to an unbelieving Oprah, led some people to think he was, to use the clinical term, nuts. Maybe the public fell out of love with him; a lot of marriages end in the husband’s mid-40s. Whatever the reason, no movie in which Cruise starred has reached even the devalued $100-million mark at the domestic box office since M:I 3 in 2005. After disappointing the American audience with his World War II drama Valkyrie and the spy caper Knight & Day (though both films did solid business abroad), he must have figured he needed to return as Ethan Hunt, in another episode of the 15-year-old Impossible franchise, to be Tom Cruise again.

In the jerry-or-Tom-built script by Josh Appelbaum and André Nemec, the mad-genius scientist Hendricks (Michael Nyqvist) is bent on acquiring Russian nuclear launch codes, and Ethan infiltrates the Kremlin to stop him. Oops, it explodes into rubble, about 30 years too late to satisfy the Reagan hawks. (“Mr. Gorbachev, blow up that building!”) “Ghost protocol,” is invoked, meaning the the Mission team is cut off from all U.S. government support. The gang has been reduced, possibly by federal cuts during the Recession, from the TV show’s six members to a bare-bones four: Ethan, über-nerd Benji (Simon Pegg), lithe looker Jane (Paula Patton) and mysterious analyst Brandt (Jeremy Renner). But they must have a lavish stash that finances their globe-hopping from Budapest to Moscow to the exotic “Bai” twins, Du- and Mum-. Maybe this branch of the Impossible Mission Force swung a loan from the International Monetary Fund — the other IMF.

Bird, who directed the feature cartoon The Iron Giant and helped create the visual style of The Simpsons before making The Incredibles and Ratatouille at Pixar, keeps things hopping as energetically as Cruise on Oprah’s couch. The opening chase and killing of a U.S. agent, Ethan’s breakout from a Russian prison and the whole Dubai sequence, which includes much Cruise dangling, a chase in a blinding sandstorm and Patton’s nifty girlfight with sexy counterspy Léa Seydoux, are expertly choreographed. The director also contributed some clever gadgets, which may have ben left over from the accoutrements he devised for the family of superheroes in The Incredibles.

But Bird’s knowing verve can’t camouflage the downtime between action scenes. Two Russian characters, a prisoner and a cop, receive a lot of exposition time, considering their minor involvement in the plot’s payoff. Ethan’s climactic tussle with Hendricks should be no-contest, but the mad scientist apparently had spare time to do a lot of reps: he’s surprisingly athletic. (Hendricks should have had a goon sidekick to even the odds against our hero.) And even the climbing of the Burj Khalifa isn’t quite enthralling enough to distract the viewer from two musings: 1. Wouldn’t hotel security, or ordinary folks photographing this Mideast miracle, have noticed that Tom Cruise was crawling up the side? And 2. In a Dubai visit that consumes about a half-hour of screen time, couldn’t the writers have introduced at least one Arab character?

For his subordinates on the Mission team, Cruise has imported actors from Indieland: Pegg (Shaun of the Dead) and Philip Seymour Hoffman (Capote) for M:I 3 and, for this installment Patton and Renner, whose respective low-budget films Precious and The Hurt Locker battled for Best Picture two years ago. The smart, lithe and sexy Patton should get larger roles in finer movies; audiences would happily dive out of a highrise to see her. Renner, though, is saddled with the role of a brooding cipher. His big speech carries zero emotional resonance; its dead air stalls the Act Three momentum. Nyqvist is another art-house favorite: in the Swedish Girl With the Dragon Tattoo film trilogy, he was the crusading journalist to the wily hacker played by Noomi Rapace — also making her Hollywood-backed action-film debut today in the Sherlock Holmes sequel.

Producer Cruise leaves the heavy flexing to leading-man Cruise, and he comfortably embodies an action hero who is superefficient but no superman (though at the Burj Khalfia he does a passable Spider-Man impression). Audiences may have forgiven or forgotten the star’s transgressions and might be ready to welcome him back in the coin of the realm any movie poobah understands. It’s just a shame Cruise’s comeback vehicle doesn’t ride more smoothly over the narrative terrain. And yes, I’m thinking it, so I might as well say it: Mission: Impossible – Ghost Protocol is no Fast Five.